Currently using a smok rsbt at 2.1ohms (target was 2) at 12-13ish watts. I'm still playing around. My kayfuns are both built similarly, 1.8 and 2.0 (I always target 2 ohms) and they do about the same as my rsbt. My RDAs are 1.3 and 1.0 ohms both dual coil, tobh and origen respectively. I'm still playing around to find my sweet spot on those.